In a known process for producing a chip card, in particular a card in which there are both means for contact-less data transmission and also a galvanic contact plane, a module which includes a semiconductor chip is fitted into a card body.
The module is preferably inserted into an opening in the card body and laminated to the card body by means of joining or the like, thereby obtaining a suitable mechanical and electrical connection.
An electrically conducting connection between the module and the card body or contacts disposed on the card body, which are in contact with a coil for making a contact-less communication with the surroundings, is afforded for example by virtue of the fact that an anisotropic conducting adhesive is applied in the region of the terminal locations and/or the connecting locations of the respective means for contact-less data transmission and the adhesive is compressed or compacted at least in the region of the terminal locations to such an extent that an electrically conducting bridge is produced.
In the case of an adhesive with conducting particles, the result of this is that the particles are in contact with each other in the region between the terminal locations and the means for contact-less data transmission, thereby resulting in the conducting connection.
The modules which are used in the production of chip cards generally have recourse to a plastic material carrier on which is arranged the semiconductor chip referred to above, possibly provided with ISO-contact surfaces. The module which is prefabricated in that way is connected to the card carrier which for example can comprise polycarbonate. That connecting operation or the step of inserting the module into the card body in a for example milled opening is usually effected by employing a glueing process, using a hot or melt adhesive.
In the situation where the aim is to produce combination cards which are suitable both for contact-less and for contact-mode use, or contact-less cards, a further contact plane with terminal locations for the induction loop must be provided. Those terminal locations are preferably disposed in a raised relationship on the surface of the module and/or on the surface or at the side faces of the opening in the card carrier. In the case of arrangements of that kind, it is then possible to effect the operation of glueing the modules and the card carriers by means of the procedure for making the electrically conducting connection, in one working operation. It has been found however that the required temperature and time conditions for producing both electrical and mechanical connections which are reliable involves close tolerances so that, in the case of process parameters which are not at their optimum, the long-term stability of cards which are produced in that way is reduced and, by virtue of the dimensions and the plastic properties of the module and of the card carrier, warping phenomena and stresses occur in the card, with the consequence of resulting in disturbed electrical connections, that is to say a lower level of reliability.
The same applies in regard to force-locking connections, for example by means of a spring element. Admittedly in this case warping or stresses can be accommodated by contact spring elements, but problems arise in regard to surface corrosion of the contacts.